1. Field of the Invention
The present invention concerns a dense fluidized bed exchanger associated with a circulating fluidized bed reactor.
It is more precisely concerned with a dense fluidized bed exchanger including a casing, the vertical longitudinal walls of which consist of tubes conveying a heat-conducting fluid, the casing being divided lengthwise into chambers separated from each other by a baffle consisting of tubes conveying a heat-conducting fluid.
2. Description of the Prior Art
An exchanger of the above kind is generally intended for use in a combustion installation comprising a circulating fluidized bed exchanger having a gas outlet leading into a separator cyclone. The solids recovered from the latter are treated in the dense fluidized bed before at least some of them are re-injected into the circulating fluidized bed exchanger.
A conventional dense fluidized bed exchanger includes a number of chambers in a casing:
a solids receiving chamber into which solids are introduced via an orifice, PA1 at least one intermediate chamber into which the solids overflow after passing over a first baffle, and PA1 a solids outlet chamber receiving the solids after they pass over a second baffle and having a solids evacuation orifice.
The intermediate chamber is equipped with a bottom fluidizing air feed casing, fluidizing air injector nozzles on the bottom wall of the chamber and a heat exchanger generally consisting of a plurality of parallel arrangements of tubes conveying a heat-conducting fluid, for example steam, disposed transversely to the chamber and suspended from the top wall of the chamber, each arrangement of tubes being connected at the bottom to a heat-conducting fluid inlet manifold and at the top to a heated fluid outlet manifold.
Dense fluidization of the solids and recovery of heat by the exchanger therefore take place in this chamber.
Making the longitudinal walls of the casing and the baffles of tubes conveying a heat-conducting fluid for enhanced heat exchange, heat recovery and thus installation efficiency is known in the prior art.
In the prior art these baffles are walls of vertical tubes extending the full height of the casing and including windows distributed across their width at the required overflow height.
This overflow arrangement does not allow solids to overflow across the full width of the casing and because the windows must be of limited width, given the continuity of the vertical tubes from the bottom of the wall to its top, this arrangement does not allow continuous and optimal flow of the solids from one chamber to the other.
The present invention solves this problem by proposing a baffle arrangement consisting of tubes that can be made to a given height and thus allow continuous and undisturbed overflowing of the solids over the baffle.